Beomaster 8000: Updating the Displays - Completed

Today I finished replacing a set of Beomaster 8000 display LEDs with SMD LEDs. This set had numerous faulty display segments so it was badly in need of repair.

I was a little disappointed that my SMD work station method of doing this task fell short of expectations. In my earlier restoration of the Beocord 9000 displays the work station method worked quite well and I felt like I only needed to perfect the process a little before it became my new way of doing these displays. Now I think that was just beginner's luck. Since that first display repair the SMD work station technique has meant a lot more rework and waste of new SMD LEDs (that had to be tossed when the installation failed).

The problem with the SMD work station is that even with minimal air flow, the SMD LEDs can shift during soldering. Even in the case where the solder pads are small I usually run into over half the LEDs not soldering in the position they need to be. With these Beosystem LED displays it is critical that the LEDs stay within a narrow range in their positioning. The reason for that is they have to fit nicely in the slots of the plastic housing that guides the light.

So after that hopeful experiment I have reverted to the tried and true manual soldering process.

To show what I am talking about here is the preparation for the Beomaster 8000 channel balance display. This picture shows the SMD LEDs in place on their solder paste ready for the heat to be applied.

After the board heater and heat gun melted the solder, the result was quite unsatisfactory.

The LEDs circled in red were not successful. I had to toss those LEDs as I don't trust them to be reused once I remove them. These SMD LED devices are pretty delicate so I don't want to risk them failing later on.

Here is the reworked board after manually repairing it with old fashioned tweezers and soldering iron. I used my de-soldering gun to clean up the excess solder.

Now that I decided to change over to the manual soldering method I prepared the next board by cleaning with alcohol and tinning the solder pads. This is the Beomaster 8000 volume level display.

Before placing the SMD LEDs I apply some solder flux with a syringe. The SMD board heater at least provides a nice way to hold the board in place while I work on it.

Here is the completed volume level display. As I did each display I was able to refer back to my photos I posted in the previous post that show the LED orientation on the pads. That was very helpful as I could just look at my smart phone for the reference photo as I placed and soldered these LEDs in place.

Next is the Beomaster 8000 function display. Here is the prepped board.

...and the finished board.

Finally the last board, the FM frequency display board. These display restorations are probably the most difficult job of the entire restoration. The work is very trying on one's patience as it is easy to get frustrated if you can't keep a steady hand. You have to be in the right frame of mind when doing this. 

Here is the last board before tinning. The marks between the pads is where I used a razor knife to cut the tiny pad the original LED mounted to. I found that trying to leave in place is risky because it is such a narrow gap. It is easy for solder to bridge that gap and cutting it out leaves a perfect gap for these SMD LED components.

Here is the board tinned and with solder flux in place on the pads.

The last board is now complete. One other note about the manual soldering process. I often just solder one side of the SMD LED to hold it, then test fit the light guide piece to make sure the LED component is centered in the slot. That is an extra step but it actually saves rework time and risk in destroying a good SMD LED. After I verified the fit I solder the other side of the LED.

Now it is time for the display burn-in test. I reworked my test jig since the last post and I am now going to leave these displays operating for 24 hours to make sure none of them are faulty.

Just for a reference I put the channel balance display completely back together (just pressed together, not permanent yet), the volume display and function display with just the light guide attached, and the FM frequency display bare. You can see the progression that the parts play in the final look of the display.

While these display modules are testing I can start work on the Beomaster display board recapping and the Microcomputer board recapping.